Ultimately, the fate of the deal rests on the whim of the incoming U.S. President.

The future of the one-off deal is unknown with President-elect Donald Trump

CANBERRA -- On weapons of mass destruction during the Iraq war, the former U.S Defence Secretary Donald Rumsfeld famously confused:

"There are known knowns. These are things we know that we know. There are known unknowns. That is to say, there are things that we know we don't know. But there are also unknown unknowns. There are things we don't know we don't know."

The future of the one-off deal with the U.S. to resettle an unknown number of "genuine" refugees currently held on Nauru and Manus Island is a known unknown, that only incoming President Donald Trump would know.

Detainees on Nauru/Manus with questions on deal are given a slip of paper, directing to US state dept general info on refugee admissions pic.twitter.com/kQBk0W8Oz5

The Immigration Department head Michael Pezzullo has revealed the transfer could take months to complete, so if it could start today, it would run into a Trump Presidency shaped by a strong anti-immigration, anti-Muslim stance.

On ABC 730 on Monday, Turnbull said he was "confident that the arrangements we've set in place will continue". Asked by host Leigh Sales if he had a plan B, the Prime Minister repeated "Well I'm confident the arrangements we've set in place will continue".

On Wednesday on radio 2GB, the Prime Minister stressed: "We have a very close and long history of co-operation with the United States on matters of this kind."

He said had a "suspicion" the new administration would not feel bound by the agreement.

To be clear, Australia does not know for certain what will happen with the deal brokered by the Obama Administration and neither do the languishing refugees on Nauru and Manus Island the deal may apply to.